Anyway, I'd said I would say something about the question. So...
Regarding the first point about whether multicultural teaching harms a child's education- no, I don't think it does. But it does depend on how it's done. For example, I think it would be something of a misnomer to call a subject Religious Education when it only teaches about Christianity (this was the case at my school, though as I'm told it's not necessarily the case everywhere). Likewise, I don't see how it makes any sense for history curriculums to focus exclusively on British or European history - it simply isn't sufficient if we want children to be informed enough to interpret or take an interest in the world they'll be reading about in newspapers.
I don't really know what the Mail means by 'anti-racism lessons', but my memory of such topics being covered in my PCHE (or whatever it was called) class is pretty dim. I was certainly an extremely intolerant teenager when it came to other ethnic groups - and so was pretty much everyone I knew at the time, but I'm not sure how deep it was. Either way, I don't remember 'anti-racism lessons' having much impact either way.
As for the second claim...
"It has also been said that Political Correctness makes racism worst not better. "
I don't believe that "Political Correctness" actually exists, so I don't agree with this statement. Every alleged example of it seems to turn it to be embellishment - or sometimes outright fabrication - on the part of the press. If anything, it seems to me that while racism - like homophobia - is far from extinct, it's much less rife than it was during my parents' generation. I can only assume that we're assumed to have gotten more PC over time, so that would imply it certainly doesn't make racism worse. Though as I say, I don't think it exists.